1. Field
The present invention relates to data communication. More particularly, the present invention relates to novel and improved techniques for multiplexing high-speed packet data transmission with conventional voice/data transmission in a wireless communication system.
2. Background
A modern day communication system is required to support a variety of applications. One such communication system is a code division multiple access (CDMA) system that supports voice and data communication between users over a terrestrial link. The use of CDMA techniques in a multiple access communication system is disclosed in U.S. Pat. No. 4,901,307, entitled “SPREAD SPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS,” and U.S. Pat. No. 5,103,459, entitled “SYSTEM AND METHOD FOR GENERATING WAVEFORMS IN A CDMA CELLULAR TELEPHONE SYSTEM.” A specific CDMA system is disclosed in U.S. Pat. No. 6,574,211, entitled “METHOD AND APPARATUS FOR HIGH RATE PACKET DATA TRANSMISSION,” filed Nov. 3, 1997 (the HDR system), issued Jun. 3, 2003. These patents and patent application are assigned to the assignee of the present invention and incorporated herein by reference.
CDMA systems are typically designed to conform to one or more standards. Such standards include the “TIA/EIA/IS-95-B Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System” (the IS-95 standard), the “TIA/EIA/IS-98 Recommended Minimum Standard for Dual-Mode Wideband Spread Spectrum Cellular Mobile Station” (the IS-98 standard), the standard offered by a consortium named “3rd Generation Partnership Project” (3GPP) and embodied in a set of documents including Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214 (the W-CDMA standard), the “TR-45.5 Physical Layer Standard for cdma2000 Spread Spectrum Systems” (the cdma2000 standard), and the “TIA/EIA/IS-856 cdma2000 High Rate Packet Data Air Interface Specification” (the HDR standard). New CDMA standards are continually proposed and adopted for use. These CDMA standards are incorporated herein by reference.
Some CDMA systems are capable of supporting multiple types of service (e.g., voice, packet data, and so on) over the forward and reverse links. Each type of service is typically characterized by a particular set of requirements, some of which are described below.
Voice service typically requires a fixed and common grade of service (GOS) for all users as well as (relatively) stringent and fixed delays. For example, the overall one-way delay of speech frames may be specified to be less than 100 msec. These requirements may be satisfied by providing a fixed (and guaranteed) data rate for each user (e.g., via a dedicated channel assigned to the user for the duration of a communication session) and ensuring a maximum (tolerable) error rate for speech frames independent of the link resources. To maintain the required error rate at any given data rate, higher allocation of resources is required for a user having a degraded link.
In contrast, packet data service may be able to tolerate different GOS for different users and may further be able to tolerate variable amounts of delays. The GOS of a data service is typically defined as the total delay incurred in the error free transfer of a data message. The transmission delay can be a parameter used to optimize the efficiency of a data communication system.
To support both types of service, a CDMA system can be designed and operated to first allocate transmit power to voice users requiring a particular GOS and shorter delays. Any remaining available transmit power can then be allocated to packet data users whom can tolerate longer delays.
In the CDMA system, each transmission source acts as interference to other transmission sources. Because of the bursty nature of packet data, the transmit power from a transmission source can fluctuate widely during the transmission of data bursts. The rapid and wide fluctuation in the transmit power can interfere with other transmissions from other sources and can degrade the performance of these transmissions.
As can be seen, techniques that can be used to efficiently and effectively multiplex high-speed packet data transmissions with voice and other transmissions are highly desirable.